1. Field of the Invention
The invention relates to a sluice for sluicing out clinker and ashes from a furnace.
2. Description of the Prior Art
The known sluice construction with only one sluice flap has certain advantages compared with the structure which besides the upper sluice flap also is provided with a lower sluice flap wherein the material, when the latter sluice flap is opened, falls down into an arrangement for carrying away said material, and wherein the two flaps lock a sluice chamber so that any risk of false draft up through the shaft when sluicing is prevented. The construction height of the inventive sluice as stated previously is far less than that of prior art, and the structural claims will therefore be substantially reduced.
Furthermore, the discharge of material for further conveyance on, for instance, a conveyor belt can be controlled so that the belt is not overloaded by a suddenly occurring heavy load, which may happen using the above-mentioned structure, when the lower flap is opened and the entire contents of the sluice chamber are discharged at the same time.
However, in the case of a sluice having only one sluice flap, the problem lies in creating a sufficiently tight lower closure for the sluice chamber.
The collecting compartment of certain known sluices of this type is arranged as a water trap, the lower part of the shaft being filled with water and having a damper extending below water level, respectively, the lower part of a shaft wall being prolonged, having outside it a water basin. By means of a scraper conveyor or other suitable conveying means, the discharged clinker and ashes are moved to the water basin, the airtight locking of the shaft being provided by the water trap. This is an excellent solution as far as the sluicing effect is concerned, but is nevertheless subject to major drawbacks. Thus, the gathering of slurry in the water basin causes blocking of grates and drains, and the abundant quantity of water that has to be drained off will be strongly polluted just as the further conveyance of the drenched clinker and ashes from the bottom of the basin results in dirtying of the surroundings. Finally, it is difficult or impossible in this way to rid a shaft of larger residual pieces which, for instance in a combustion plant for trash, often will be present together with the clinker and ashes falling into the shaft. This results in such residual pieces becoming lodged in the shaft or at the best removed from there with much difficulty. In any case, the construction of such plants will have to be very strong and robust and will be correspondingly expensive to install and maintain where, for instance, there is question of hard wear caused by a scraper conveyor.
It has also been suggested to form the water trap by extending the bottom of the shaft to incline upwards past the side facing the downwards protruding damper shaft wall like a scraper ramp provided with side walls, said ramp ending in a discharge edge situated higher than the lower edge of the downwards protruding shaft wall, and over which the scraped clinker and ashes are pushed and fall down into a transportation system for further disposal. In this structure, where the wall part protruding down in the water possibly may be displaceable in a vertical direction through the action of the waste pushed out, the above disadvantages as regards lodging and removal of large residual pieces do not manifest themselves very markedly. However, particulary large residual pieces, common in the case of the burning of waste, often will be incapable of pushing the slidable wall part up, so that the removal of such pieces involves extra work. Furthermore, the drenched material pushed over the edge of the ramp will give rise to considerable drawbacks, just as the lack of a proper water basin will make a frequent supply of water necessary in order to maintain the water trap.
However, it is also known to sluice out without the use of a water trap, as the dry clinker and ashes that have fallen down into the collecting compartment are pushed out through the side of the collecting compartment respectively through a tunnel-like outlet at the bottom of the shaft wall by means of a suitable conveyor, for instance a screw conveyor, or a suitable piston in the tunnel which by its piston rod extending through a bushing in the shaft wall is moved backwards and forwards and gradually pushes the material out through the tunnel. When this material contains a relatively large quantity of ashes in relation to residual pieces the part that at any time remains in the tunnel will form a sufficiently tight closure for a sluice chamber. However, in this structure there is a great risk of lodging of the material, and larger residual pieces or pieces of clinker smelted together may result in overload and will only with difficulty, if at all, be discharged through the tunnel, their removal thus demanding difficult manual work.
It is the purpose of the invention to provide a sluice of the type stated previously, in which the drawback stated in the above-mentioned known structure will not be present, while the stated advantages of these structures are maintained. In the sluice according to the invention the sluicing out takes place without the use of a water trap, and the conditions for easily sluicing out voluminous pieces of the clinker material are particularly favorable.